An insulating glass unit (i.e., an “IG unit” or “IGU”) typically includes a pair of generally parallel panes held in a spaced-apart relationship by a spacer. The basic structure of a conventional double-glazed IG unit includes peripheral inner surfaces of the panes joined by a space to define a between-pane space. While many standard IG units simply contain air, high performance IG units are sometimes filled with insulating gas to increase the insulating capacity of the units. Filling the between-pane space of an IG unit with insulating gas advantageously increases the “R” value (i.e., the resistance to heat flow through the unit) of the resulting unit. Ideally, the between-pane space is filled with a gas that is heavier and less thermally conductive than air. Argon is commonly used as an insulating gas fill. Krypton is an even better insulator than argon. However, it is also significantly more expensive. Other inert gases can be used as well. The glass panes are hermetically sealed to retain the gas within the interior space defined by the separate panes of glass and respective spacers. These IG units have a rectangular profile and are generally positioned within door frames and sliding glass doors.
Pet doors are utilized to provide access for pets such as cats and dogs to exit and enter homes without the need for an owner to repeatedly open and close doors. Pet doors are commonly known and used. Pet doors are customarily designed for integration with doors of a house. Holes are cut out of the door frame and the pet door is installed in the frame of the door.
However, in certain circumstances, where the glass is utilized throughout the majority of the door, such as in a sliding glass door on a patio, the pet door is larger than the frame and hence the frame cannot be cut for installation. You cannot cut the tempered glass in the door or it will shatter.
U.S. Pat. No. 7,784,430 illustrates a common solution for installation of a pet door in a sliding patio environment. An independent pane or door section which includes a pet door is positioned adjacent to the regular sliding door pane in sliding frame. While suitable for its intended purpose, this construction does not provide for the insulation benefits of a well sealed sliding door system.
Alternatively, U.S. Pat. No. 4,760,872 discloses a pet door for installation in a fixed or moveable glass door or window. This patent discloses that the single pane of glass has been cut for installation of the pet door. The pane is encased in a frame and with the corner cut out; the pet door is adapted for being received within the remaining portion of the frame. While suitable for its intended purpose, such a construction of a pet door is not suitable for an insulated glass unit as the moment the glass is cut, the inert gases will escape.
Accordingly, there is a need in the art for a pet door which is integrated with an insulated glass unit to provide the thermal benefits of the insulated glass unit while permitting utilization by a pet.